Railway track circuit apparatus



2 Sheets-Sheet 1 Filed May 51, 1953 m m m n H MC N MM 1938. P. N. MARTIN RAILWAY TRACK CIlIRCUIT APPARATUS Filed May 31, 1933 2 Sheets-Sheet 2 INVENTOR PaulMMamm BY mu" ATTORNEY Patented Jan. 4, 1938 NETED srras w ser orrics RAILWAY TRACK cmcm'r APPARATUS Application May 31, 1933, Serial No. 673,605

18 Claims.

My invention relates to railway track circuit apparatus, and has for an object the provision in apparatus of this character of a track relay combination which can be adjusted to provide as nearly as possible maximum shunting sensitivity under infinite ballast resistance condition. I accomplish this result by providing a track relay combination which may be adjusted to pick up and release on as nearly as possible the same values of current and voltage. Apparatus embodying my invention also provides improved shunting sensitivity under all conditions, and re duces the shunting time for any value of train shunt resistance.

I will describe several forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic View showing one form of track circuit apparatus embodying my invention. Figs. 2,3, 4, 5, and 6 are views similar to Fig. 1, but each showing a modified form of relay combination also embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters I and I designate the track rails of a railway track, which rails are divided byin sulated joints 2 to form a track section A--B. A source of current C is connected across the rails at one end of this section through a current-limiting resistor 3. this source, as here shown, being a battery. Located at the other end of the section is a primary relay P and a secondary relay S. The primary relay P is provided with a pick-up circuit which is connected across the rails l and 1*, which circuit passes from rail I, through the entire operating winding Q3 of relay P, and the back point of contact 5 of relay S to rail l Relay P is also provided with a holding circuit which passes from rail I, through a portion of the operating winding Hi to a tap l6, and then through a resistor 9 and the front point of contact 6 of relay S to rail l Contact 6 is a continuity transfer contact, meaning that when the relay S closes, the front point of contact 6 closes before the back point of this contact opens. It will be seen from the foregoing that the pick-up circuit for relay P includes the entire operating winding of this relay, whereas the holding circuit includes only a portion of the operating winding and a resistance 9 which compensates for the reduced resistance of the relay winding. The secondary relay S is provided with ing slow pick-up characteristics, and may, for

example, be a -ohm relay. Relay S is provided with additional contacts, such as 1 and 8, which may be used to control circuits for signals or any other desired trafic governing apparatus.

The operation of the apparatus shown in Fig. 1, is as follows: Normally both relays P andS are closed, so that the holding circuit for relay P is connected across the rails of section A-B. The resistor 3 is adjusted to substantially the same value as it would be for an ordinary track relay having the same resistance and working current as relay P with its full winding l3. Then when a train enters this section, the shunt across the rails formed by the wheels and axles causes relay P to release very rapidly because only a portion of the winding of this relay is connected across the rails. After a time interval determined by the slow releasing characteristic of relay S, the latter relay will also release, thereby closing the pick-up circuit for relay P across the track rails, but as long as any portion of the train occupies section A-B, the voltage across winding l3 will be less than the pick-up voltage of relay P. When the entire train leaves section AB, the voltage across winding l3 will rise above the pick-up, value of relay P, so that this relay will close. Relay S will then close, thereby opening the pick-up circuit for relay P and closing the holding circuit for the latter relay.

If the train is of light weight and conditions are such that it provides a high shunting resistance (within limits of course), it will still cause relay P to release whereas an ordinary track relay would remain in the picked-up position. If the resistance of the train shunt varies intermittently, the primary relay P may pick up and release, following the variations in train shunt resistance, Without allowing relay S to pick up.

The number of turns in winding l3 that can be cut out when the holding circuit for relay P is closed, is determined chiefly by the ratio of the release value of this relay to its pick-up value. When relay P is a standard track relay, in so far as the resistance of its winding is concerned, approximately 25% of the total turns of winding l3 can be cut out, provided that the value of resistor 9 is substantially equal to the resistance of the turns which are cutout. The parts may be so proportioned that both the release current and. the release voltage of the relay combination are made to approach the pick-up current and. the pick-up voltage, respectively, so that the relay combination produces the maximum shunting sensitivity obtainable with a track circuit of any length.

Referring now to Fig. 2, the apparatus shown in this view is the same as that shown in Fig. 1, except that a front contact 4 of relay P is included in the holding circuit for this relay. The operation and characteristics-of this form of'the apparatus are similarto those of the apparatus shown in Fig. l with the exception that the inclusion of contact 4 in the holding circuit .for relay P guarantees the release of relay S and prevents pickup of relay P over itsown holding circuit. That is, once contact 4 opens,'a release of relay S is insured because relay P will have no energizing circuit until such time asback contact 6 of relay S closes. V

I Referring now-to Fig. 3, the apparatus shown-in this view is the same as that shownin'Fig. 1, ex-

cept that the holding circuit for relay P is connected directly across the track rails l and l and does not include a front point 6 of the sec ondaryrelay'S. "This eliminates the necessity for making conact '6 a continuity transfer contact. For convenience of illustration, the'winding of relay P .isillustrated in the'for'm of two coils I3 and I3, corresponding to the two coilsjof the usual electromagnet. The pick-up circuit for relay P includes the entire winding of thisrelay as before and also the'back point of contact 6 of relays, whereas the holding circuit includesonly the left-hand coil 13 and the lower part of the right-hand coil 13 In Fig. 4 the apparatus is the same as in Fig. 3, except that the holding circuit "includes a front contact 4 of relay P as in-Fig. 2.

With the apparatus shown in Figs. 3.and 4, and

7 especially with that shown in Fig. '3, it is advantageous'for the resistance of that part of coil 13 which is cut out when relay S picks upto be as large as possible, thereby allowing the battery resistor 3 (Fig. 1) to be the same or nearly the same as it would be for the apparatus :shown in Figs. land 2. This may-be accomplished by the arrangement of connections shown in 5, wherein the lower end-of coil 13 is connected with the lower'end of coil l 3 throughback contact 6, and the resistor 9 is connected 'between'the lower end of coil l3 and the pointiB in coil'l3 In Figs. 3 and 4, the higher resistance turns or foutside turns which are cutout whenrelayS picks up are located the 'upper half of coil 13 as therein within the scope of theappended claims.

viewed in the drawings. In Figs:fi andfiytheoutside turns arelocated in the lowerhalf of coil 13 ihe apparatus shown in Fig. 6 is the same as that shown in Fig. 5, except that the holding-circult forrelay P includesa front contact 4 of this relay as in Figs. 2 and 4.

Although I have herein shown and described Z only a few forms of track circuit apparatus embodying my invention, it is understood that various changes and modifications may be made without departing from the spirit and scope of my invention.

Having thus described my invention, whatI claim is: r r

1. In combination with 'a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of the primary relay, a holding circuit for said primary relay connected across the rails of said section and including a front contact of said secondary relay and a front contact of said primary relay as well as only a portion of the operating winding of the primary relay and a resistance, and a circuit for said secondary relay including a front contact of said primary relay and a source of current.

2. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pick-up circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of the primary "relay, a holding circuit for said primary relay connected across the rails of said section and including a front contact of said primary relay as well as only a'portion of the operating winding of the primary relay and a resistance, and a circuit forsaid secondary relay including a front contact of said primary relay and a source of current.

3. In combination with a section of railway track and a source of current connected across the rails of said section, aprimary relay and a secondary relayfa pick-up circuit for said prition and including a back contact of said secondary relay as well as the entire operating winding of the primary relay, a shunt path around said track and asourcecf current conn'ectedacross therailsof saidsection, a primary relay and a secondary relay, a pick-up circuit for said-primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entirecperating winding-of the-primary relay, a holding circuit for said primary relay connected across the rails of said section "and including-a front contact of said primaryrelay as well as only aportion of the operating winding of the primary relay and a resistance, the portion of the primary relay winding which is not included in said holding circuit being outside turns of one of the coils of the primary relay, and a circuit for-said secondary relay including a front contact of said primary relay and a source of current.

5. In combination with a section of railway 7 mary relay connected across the rails of said sectrack and a source of current connected across" the rails of said section, ajprirnary relay and a secondary relay, a'pick'up circuit for said primary relay connected across the rails of said section and including a back. contact of said secondary relayaswell as the entire operating winding of the primary relay, a shunt path around-said back contact and a portion of said operating windin'gnn'd including a resistance whereby a holding circuit for said primary relay is provided which excludes said winding portion and includes said resistance, the portion of the winding of the primary relay whichis not included in'said holding circuit comprising turns of relatively high resistance per turn for decreasing the power consumed from said source and for increasing the shunting sensitivity of said track section, and a circuit for said secon ary relay including a front contact of said primary relay and a source of current. V I

6. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of sai section and including a back of secondary relay as well as the entire cper ting winding of the primary relay, a holding circuit for said primary relay connected across the rails of said section and including a front contact of said secondary relay and a front contact of said primary relay as well as only a portion of the operating winding of the primary relay, and a circuit for said secondary relay including a front contact of said primary relay and a source of current.

track and a source of current connected across 'the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of the primary relay, a holding circuit for said primary relay connected across the rails of said section and including a front contact of said primary relay as well as only a portion of the operating winding of the primary relay, and a circuit for said secondary relay including a front contact of said primary relay and a source of current.

8. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including the back contact of said secondary relay as well as the entire operating winding of the primary relay, a shunt path around said back contact and a portion of said operating winding whereby a holding circuit for said primary relay is provided which excludes said winding portion, a portion of the winding of the primary relay which is not included in said holding circuit comprising turns of relatively high resistance per turn for decreasing the power consumed from said source and for increasing the shunting sensitivity of said track section, and a circuit for said secondary relay including a front contact of said primary relay and a source of current.

9. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay receiving energy from said rails, a secondary relay, means including a back contact of said secondary relay for supplying pickup energy to said primary relay, means including a front contact of said primary relay for supplying holding energy to the primary relay, and means for energizing said secondary relay independently of said track source of current, said means including a front contact of said primary relay.

for supplying pickup energy to said primary re-- lay, means including a front contact of said primary relay and an impedance for supplying holding energy to the primary relay, and means for energizing said secondary relay independently of said track source of current, said means including a front contact of said primary relay.

11. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of the primary relay, a constantly closed shunt path around said back contact and a portion ofsaid operating winding and including an impedance whereby a holding circuit for said primary relay becomes effective when said secondary relay is energized and said back contact is open, said holding circuit excluding said winding portion and including said impedance, and a circuit for energizing said secondary relay including a front contact of said primary relay.

12'.In combination with a section of railway track anda source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of the primary relay, a constantly closed shunt path around said back contact and a portion of said operating winding whereby a holding circuit for said primary relay becomes effective when said secondary relay is energized and said back contact is open, said holding circuit excluding said winding portion, and a circuit for energizing said secondary relay including a front contact of said primary relay.

13. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including the back point of a continuity transfer contact of said secondary relay; a holding circuit for said primary relay connected across the rails of said section and including the front point of said continuity transfer contact, a front contact of said primary relay, and an impedance; and a circuit for energizing said secondary relay including a front contact of said primary relay.

14. In combination with a section of railway track and a source of current connected across the rails of said section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including the back point of a continuity transfer contact of said secondary relay as well as the entire operating winding of the primary relay, a holding circuit for said primary relay connected across the rails of said section and including the front point of said continuity transfer contact as well as a front contact of the primary relay and only a portion of the operating winding of said primary relay, and a circuit for energizing said secondary relay including a front contact of said primary relay.

15. In combination with a section of railway track anda'source of current connected; across the railsyof said section, a primary relay and, a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and f including .a back contact of .said secondary relay as well as the entire operating winding. of the primary relay, a holding circuit for said primary relay connected across the rails of said section and including a front contact of the primary relay as well as only a portion of the operating winding of said primary relay and an impedance,

and a circuit for energizing said'secondary relay 7 including a front contact of said primary relay.

16:. In: combination with a section of railway track and a source of'currentv connected across.

the-rails of said'section, a; primary relay having a winding comprising two sections, a secondaryl relay, a pickup circuit, for said'primary relay connectedaeross the rails of said section and including both sections ofv said winding as. well as a back con-tactci said secondary relay interposed between said two sections, a. shunt'path around said back contact and a portion of thewi-nding of oneof said sections whereby a'holdingcircuit for said primary relay is provided which excludes said winding portion, and. a circuit for energizing; said secondary relay includinga front contact of said primaryrelay.

l7. In combination with-a section of railway gottrack and a source of current connected across the rails of said section, a primary relay and a is energized and said back contact is open, and

an energizing circuit for-said secondary relay including a front contact of said primary relay.

18. In combination with, a section of railway track and a source of current connected across the rails, of said'section, a primary relay and a secondary relay, a pickup circuit for said primary relay connected across the rails of said section and including a back contact of said secondary relay as well as the entire operating winding of said primary relay, a constantly closed holding circuitfor said primary relay including a connection around a portion of said operating winding, said holding circuit being alone effective to maintain the'primary relay picked up when said, secondaryrelay is energized and said back contact is-open, and an energizing circuit for. said secondary relay including a front contact of said primary-relay.

PAUL N. MARTIN. 

